13279 A commissionaire remains all night in a little lodge at the foot of the stairs, and is in the habit of making coffee at his spirit-lamp for any of the officials who may be working overtime.
13280 I rang the bell, therefore, to summon him.
13281 'To my surprise, it was a woman who answered the summons, a large, coarse-faced, elderly woman, in an apron.
13282 She explained that she was the commissionaire's wife, who did the charing, and I gave her the order for the coffee.
13283 'I wrote two more articles, and then, feeling more drowsy than ever, I rose and walked up and down the room to stretch my legs.
13284 My coffee had not yet come, and I wondered what the cause of the delay could be.
13285 Opening the door, I started down the corridor to find out.
13286 There was a straight passage dimly lit which led from the room in which I had been working, and was the only exit from it.
13287 It ended in a curving staircase, with the commissionaire's lodge in the passage at the bottom.
13288 Half-way down this staircase is a small landing, with another passage running into it at right angles.
13289 The second one leads, by means of a second small stair, to a side-door used by servants, and also as a short cut by clerks when coming from Charles Street.
13290 'Here is a rough chart of the place.'
13291 'Thank you.
13292 I think that I quite follow you,' said Sherlock Holmes.